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Spring Boot 2 - receive response message for the request message using RabbitMQ (RPC)

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Creg

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In this article, we would like to show you how to create Spring Boot 2 application that sends request messages and receives response messages using RabbitMQ RPC pattern.

RabbitMQ RPC pattern in Spring Boot 2 application.

In Spring Boot 2 application using RabbitMQ RPC pattern, it is necessary to send message from producer to consumer attaching REPLY_TO and CORRELATION_ID headers, that indicate to consumer which producer by what action sent message.

Spring Boot 2 Applications

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In this section, we can find a simplified solution that realizes the request-response pattern.

Hint: the article extends project in this article.

Producer application example

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The main idea of the producer is to send messages using convertSendAndReceive() method.

ProducerController.java file:

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package com.example.demo;
​
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
​
@Controller
public class ProducerController {
​
    @Autowired
    private RabbitTemplate rabbitTemplate;
​
    @RequestMapping("/test")
    @ResponseBody
    public void test() {
        String requestMessage = "Testing request message...";
        String responseMessage = (String) this.rabbitTemplate.convertSendAndReceive("my-queue", requestMessage);
        System.out.println("Response message: " + responseMessage);
    }
}

Hint: if the time of the waiting for the response is long we can change timeout.

Consumer application example

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The main idea of the consumer is:

listen for a request messages,
send a response message to the queue indicated in AmqpHeaders.REPLY_TO header that indicates the request message producer,
indicate proper correlation id parameter in the response message to let the producer know on what request message reply is sent.

ConsumerService.java file:

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package com.example.demo;
​
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.amqp.support.AmqpHeaders;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.handler.annotation.Header;
import org.springframework.stereotype.Service;
​
@Service
public class ConsumerService {
​
    @Autowired
    private RpcService rpcService;
​
    @RabbitListener(queues = "my-queue")
    public void handleMyQueue(
            @Header(value = AmqpHeaders.REPLY_TO, required = false) String senderId,
            @Header(value = AmqpHeaders.CORRELATION_ID, required = false) String correlationId,
            String requestMessage
    ) {
        System.out.println("Request message: " + requestMessage);
        if (senderId != null && correlationId != null) {
            String responseMessage = "Testing response message...";
            this.rpcService.sendResponse(senderId, correlationId, responseMessage);
        }
    }
}

RpcService.java file:

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package com.example.demo;
​
import org.springframework.amqp.core.MessageProperties;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
​
@Service
public class RpcService {
​
    @Autowired
    private RabbitTemplate rabbitTemplate;
​
    public void sendResponse(String senderId, String correlationId, Object data) {
        this.rabbitTemplate.convertAndSend(senderId, data, message -> {
            MessageProperties properties = message.getMessageProperties();
            properties.setCorrelationId(correlationId);
            return message;
        });
    }
}